Performance of WC-VC-Co thermal spray coatings in abrasion and slurry erosion tests

Thermal spray coatings based on tungsten carbide are widely used in wear applications. This paper presents results obtained from commercial WC-12 wt.%Co and WC-17 wt.%Co as well as experimental WC-10 wt.%VC-12 wt.%Co and WC-10 wt.%VC-17 wt.%Co coatings. The coatings have been deposited on stainless steel substrates using a high pressure high velocity oxy-fuel (HP/HVOF) Tafa® JP 5000™ thermal spraying system. They have all been tested under identical conditions in order to compare their resistance to abrasion and slurry erosion. Similar tests have been carried out previously in our laboratory [H.L. de Villiers-Lovelock, S. Luyckx, Preliminary investigation on the potential of VC-WC-Co HP/HVOF powders and coatings, in: C.C. Berndt (Ed.), Proceedings of the First International Thermal Spray Conference, Montreal, Canada, 8-11 May 2000, pp. 647-656] [1] but gave inconclusive results which were found due to the VC-containing powders (WC-VC-Co) not being optimal. The tests have now been repeated with optimized WC-VC-Co powders. The present results show that the WC-VC-Co coatings produced with the optimized powders exhibit higher abrasion resistance then commercial WC-Co coatings. In slurry erosion, the best performance of the VC-containing coatings is as good as that of the commercial WC-Co coatings. The role of VC and cobalt in the wear process of the coatings is discussed.